Assotsiativnyj simbioz pochvennykh diazotrofnykh bakterij i ovoshchnykh kul' tur.

The capacity of associative diasotrophes strains, obtained by the method of analytical selection, to permanent reproduction and growth in the rhizosphere (rhizoplane) of non-leguminous species (vegetables, first of all) was studied. It was presumed that they should conserve their initial properties, such as nitrogen fixation, phytohormones and some fungistatic agents production. The probability of positive effect of these bacteria on crops growth and production has been assessed. The objects of analytical selection of associative diasotrophes active strains were the rhizoplane of cucumber, tomato, pepper, lettuce and of some other plants. 338 associations were obtained from the rhizoplane of 195 kinds and hybrids of cucumber. Facultative-anaerobic diasotrophes proved to be dominant, they are members of Enterobacteriaceae family and of Klebsiella genus. Representatives of Bacillus genera were found, whereas Azotobacter, Azospirillum, Xanthobacter and Clostridium were absent. Pseudomonas bacteria were associated with diasotrophes-enterobacteria in the microbial associations under study. Determination of nitrogenase activity by numerous associations separated from cucumber rhizoplane permitted to obtain a set of enterobacteria, with the strain TSKhA-91 being especially effective. It was identified as Klebsiella planticola. Further investigations demonstrated high capacity of these bacteria to the biosynthesis of growth substances. Thus, in case of strong dilution (1:1000) of the bacterial culture (without cells) a considerable increase of roots (by 86%) and stems (by 80%) growth was registrated for the test plant-garden-cress. Moreover, Klebsiella planticola was revealed to have a fungistatic activity for some phytopathogenic fungi: Penicillium, Aspergillus, Thelaviopsis, Alternaria, Mucor. The fungistatic activity of these bacteria may be favourable for the biological protection of plants in green houses. Klebsiella planticola was investigated in terms of its capacity to be adsorbed on plant roots and to colonize them, and in was found out that bacteria were restricted to roots and were practically absent in the soil. The Klebsiella planticola displays a high nitrogen fixating capacity, is able to synthesize growth substances and to inhibit the phytopathogenic fungi. Studies of Klebsiella planticola inoculation influence on the yields of vegetables showed a distinct positive effect: cucumber yield grew by 21-23%, that of tomatoes - 31%, of potato - 21%, of pumpkin - 31%. Klebsiella planticola strain is recommended as a bacterial fertilizer for vegetables, mainly in the green houses for obtaining ecologically pure production.